Amateur-built INTERSTATE S-4 accident near Anchorage, Alaska, September 11, 1999
On September 11, 1999 at about 7:45 pm local time, a amateur-built INTERSTATE S-4, registered N4BZ, was substantially damaged in an accident near Anchorage, Alaska (Sand Lake airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's inadequate planning/decision, and his failure to maintain directional control of the airplane. Factors in the accident were a short runway/lake area for departure, and the pilot's extension of the landing gear steering system (water rudders) during the takeoff run.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 11, 1999 · about 7:45 pm local time
- Place
- Anchorage, Alaska · Sand Lake · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built INTERSTATE S-4 INTERSTATE
- Registration
- N4BZ · registry record · serial 004
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was taking off from a private lake in a homebuilt/experimental float equipped airplane. While waiting for a departure clearance, he was taxiing in a tight left turn in a cove located at the west end of the lake. The water rudders were extended and displaced to the left. The pilot said the water rudders are stiff when they are deployed. After receiving his clearance, he began his departure from the cove. During the takeoff run, he left the water rudders extended. When the airplane became airborne, he said the airplane continued to turn left. He was unable to prevent the airplane from colliding with a small boat dock, and the top of a small boat. The airplane then collided with trees along the edge of the lake. An FAA inspector said the distance from the cove used for departure to the dock was about 500 feet. The distance from the dock to the trees was about 100 feet. In the Pilot/Operator report (NTSB form 6120.1/2) submitted by the pilot, he stated, in part: '...At rotation, could not control P-Factor of engine with max right rudder.' The pilot also indicated there was no mechanical malfunction/failure.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: private
- Ratings: single-engine land; single-engine sea; instrument: airplane
- Flight time: 900 hours in all; 33 in this make and model; 20 in the last 30 days
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Last inspection: annual inspection, July 28, 1999; 12 hours since
- Maximum gross weight: 2,400 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-320 (piston); 0 hours total
The flight
- Destination: Butterfly Lake AK
- Flight plan: none
- Runway 9, 500 ft
Weather at the time
- Light: daylight
- Visibility: 30 statute miles
- Sky: clear
- Temperature: 50°F (10°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N4BZ the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.